Summary of findings 2. Comparisons of routine laboratory tests for COVID‐19 with sensitivity and specificity higher than 50%.

Comparisons of routine laboratory tests for COVID‐19 with sensitivity and specificity higher than 50%
	Number of studies (number of cases/number of non‐cases)	Fixed specificity	Summary sensitivity corresponding with fixed specificity (95% CI)	Interpretation of the results: tests used in a hypothetical cohort of 1000 people tested for COVID‐19, at a pre‐test probability of 5% and 36%a
				Prevalence	TP	FP	FN	TN
Lymphocyte Count Decreaseb	13 studies (2752/1066)	53%	64% (28% to 89%)	0.05	32	447	18	504
				0.36	230	611	130	339
C‐reactive protein (CRP) increaseb	14 studies (997/1284)	53%	58% (45% to 70%)	0.05	29	447	21	504
				0.36	209	611	151	339
IL‐6 increase at a lower threshold	4 studies (86/130)	58%	73% (36% to 93%)	0.05	37	399	14	551
				0.36	263	579	97	371
IL‐6 increase at a higher threshold	4 studies (86/130)	74%	59% (25% to 86%)	0.05	30	247	21	703
				0.36	212	476	148	474
CI: confidence interval; FN: false negative; FP: false positive; TN: true negative; TP: true positive. Included studies defined a positive test result as an increase or a decrease compared to normal range values, or both.

^aThe median pre‐test probability in the meta‐analyses varied between 27% and 84%, meaning that the included studies are not representative for situations where the prevalence is 5% or lower. The median prevalence over all the single‐gate studies was 36%.
^bThe direct comparison between lymphocyte count increase and C‐reactive protein (CRP) increase (9 studies) showed that CRP was considerably more accurate than lymphocyte count increase: relative diagnostic odds ratio (DOR) was 2.02 (95% confidence interval 1.47 to 2.78). As the confidence intervals of all the DORs in the indirect comparisons included a non‐informative value (i.e. DOR = 1), a relative DOR of 2 does not mean the alternative is much more informative.